The present invention relates to disposable battery packs containing electrochemical cells. More particularly, the present invention has features relating to such packs that are disposable and which contain at least one cell that requires a gas exchange with ambient atmosphere.
Most high-drain portable electronic devices are powered by secondary or rechargeable batteries. Examples of such high-drain devices are cellular telephones, notebook computers, camcorders, and cordless hand-tools. The reason primary batteries are unattractive in such applications is that the life-span of a typical primary or single-use batteries is so short, and the cost so high, that they ultimately prove too costly for long-term use. In addition, their weight alone would discourage a person from carrying enough primary batteries for a long-term operation of the device. For example, a cellular telephone with alkaline batteries would last about as long as a single charge of a nickel-metal-hydride battery, but in the long term, cost far more per unit energy. A nickel-metal hydride battery, though initially expensive, costs only pennies to recharge.
New primary battery technologies have emerged that have, in principle at least, the ability to offer sufficient energy and power at a sufficiently low cost to make these batteries attractive for high-drain portable devices. One such technology is metal-air batteries, for example zinc-air batteries. In a zinc-air battery, one of the electrodes of the battery uses oxygen that can be supplied by ambient oxygen. Since oxygen is available everywhere, a zinc-air battery need house only one consumable electrode. Because of this, the energy capacity per unit weight is magnified greatly. Unfortunately, the intrinsic benefits of electrochemical cells that use air as an electrode are attended by some serious technical problems.
Typical zinc-air cells, such as those in hearing aid batteries, have holes in their casings to admit air. These holes permit oxygen to diffuse into the cell and also permit water vapor to escape. For larger batteries with high power capacity, multiple cells must be used. In such large combinations, the exchange of these gases becomes a real problem as discussed below.
Although zinc-air batteries have high energy densities, they are moderately low on power. To increase their power, large amounts of oxygen must be supplied. This creates some obvious design problems for hand-held consumer devices. Many small portable electronic devices have battery compartments that are narrow with a small opening for exchanging the batteries when they are depleted. These configurations provide little area for the exchange of air gases with the outside. A typical zinc-air battery for use in a hearing aid would require a total surface area of approximately 200 cm2 to generate sufficient power to operate a typical digital telephone. To expose such a large area to the outside would require a dramatic rethinking of the way batteries are housed by appliances.
One solution is to pump air into and through the battery pack. So called active air management systems can pump large amounts of air through a small opening. However, these systems usually require an air pump that can be difficult to fit into the cost and volume constraints of a disposable battery.
An additional problem with metal-air batteries is the fact that, because oxygen must enter the battery, water vapor can leave the battery. As such, metal-air batteries are susceptible to desiccation in low humidity environments, which can destroy their ability to function.
Leakage of water between or onto metal-air batteries is also a concern. Water from a multitude of sources can potentially enter the battery pack. Intruding water can then contact the metal-air battery cells and cause electrical shorts. Sources of such water include sweat from the person handling the device, moisture from speaking near or into the device, or simply from water spilled onto the device.
Finally, portable electronic devices place constraints on battery weight and volume. The battery cell must be sized to deliver, cost effectively, required power while also conforming to the various shapes, sizes, voltages, amperages, etc. of cellular telephones, notebook computers, camcorders, and cordless hand-tools.
A battery pack, in at least one embodiment of the invention, contains at least one battery cell that uses an air electrode. One of the goals of the invention is to improve the passive exchange of air gases with electrochemical cells housed in the pack. The embodiments described below provide compact configurations that are compatible with small portable high current electronic devices. Further, design strategies and guidelines are provided for applications other than those discussed herein.
A paradigmatic use of the invention is as a primary battery for cellular or mobile telephones. The battery pack is capable of replacing or supplementing existing, commonly used, secondary (rechargeable) power supplies such as a nickel-metal hydride battery.
Typically, metal-air battery cells include an outer case wall having one or more holes to permit diffusion of oxygen from ambient air. The metal-air battery cell generates power through electrochemical reactions. To generate power, an oxygen-reducing catalyst, in an air cathode inside the battery cell, catalyzes the conversion of oxygen to hydroxyl ions. The hydroxyl ions then migrate to the anode where the anode metal oxidizes. Electrons are liberated by the anode and pumped through the load to offset the deficit generated by the oxygen reduction in the cathode. A preferable metal for the anode in these types of battery cells, is zinc.
For metal-air batteries to provide high power, large amounts of oxygen must pass into the metal-air battery cells (up to 0.0032 cc/sec/cm2). This creates some obvious design problems for hand-held consumer electronic devices. Small portable electronic devices provide little surface area for air access through the battery pack case. Moreover, the metal-air battery cells themselves must be designed so as to insure adequate oxygen delivery through the cell.
The battery pack is designed in accord with the goal of delivering an adequate supply of oxygen to generate enough current to power computers and cell phones while optimally balancing the sometimes competing goals of improving the efficiency of supplying oxygen to the cathode and minimizing moisture loss. In addition, the design is in accord with the goals of providing a compact and flexible mechanical configuration, reducing the cost and complexity of the pack, and increasing the energy density of the pack.
Most of the battery pack features discussed herein stem from the advantages and constraints of a prism-shaped cell design.
At the cell level, the total area, the placement, and the size of each hole on the battery cell reflect an optimization of the needs of manufacturability, efficient oxygen supply to the cathode, and minimal moisture loss as discussed in the applications mentioned above.
To support the cell""s demand for oxygen, an ideal scenario would be for each cell to be continuously immersed in fresh, oxygen rich air. In that case, the driving gradient of oxygen is maximized. The pack designs described herein employ various principles in combination to provide oxygen delivery at a rate that is compatible with the high current demands of the above-noted applications.
When arranging cells inside the case, as many cells as possible should be oriented so that their gas-exchange walls face an external wall of the housing. (Note that a single cell may have more than one gas-exchange wall) The external wall of the housing is populated with holes. The short distance between the gas-exchange walls and the ambient air coupled with the abundance of holes on the housing ensure that oxygen can passively diffuse at a rate adequate to satisfy the oxygen requirements of the cells. The number of cells needed to generate the necessary level of current and to hold a sufficient quantity of energy, together with the form-factor requirements, may make it impossible for a designer to orient the cells so that they all face the exterior of the housing. Additionally, cells can be added and arranged to define internal plenums within the housing. Ventilation holes on opposite sides of the plenum permit bulk flow as well as a diffusion of air so that sufficient oxygen can reach every cell. This strategy requires adherence to an array of design principles that are set forth below.
Bulk flow can result from buoyancy (resulting from heat generated by an attached device or generated by the battery cells themselves) or movement of ambient air relative to the device. The latter happens, for example, when the person moves the device around, when a gust of wind passes through, etc. The former, thermally-driven, bulk air flow is called the xe2x80x9cstack effect.xe2x80x9d The effect is caused by the pressure difference resulting from buoyancy caused by the difference in temperature inside the case compared to that outside the case. The temperature difference is maintained when the device or battery cells generates heat, such as during a high-power operation or transiently when the device and battery pack are moved from an environment at one temperature to an environment at a different temperature.
The battery pack case preferably contains holes all throughout the case, which, because of their cumulative open area and location, ensure adequate oxygen delivery to the battery cells. Alternatively, a porous plastic or semipermeable membranes or materials, which permit a sufficient air exchange through the battery pack case, may be used in place of holes.
Ingress, into the battery cell, of the oxygen necessary for discharge is driven by Fick""s Law. A difference in the partial pressure of oxygen across the surface of the battery cell forces air to diffuse through the air access holes of the battery cell and into the air cathode. This difference in partial pressure of oxygen across the surface of the metal-air battery cell occurs due to the depletion of oxygen inside the battery cell when the oxygen is converted to hydroxyl ions.
The inadvertent blockage of holes on the battery pack case can also pose a problem in the supply of oxygen to the metal-air battery cells. To alleviate this problem, the battery pack case must have sufficient air access openings that remain unobstructed when the case is in contact with an obstruction to allow adequate air access. Alternatively, the battery pack case surface provides a plurality of projections to maintain the blocking surface a minimum distance away from the air access holes, thereby preventing blockage. Alternatively, the air access holes are located in a plurality of indentations, recesses, or grooves on the surface of the battery pack case, preventing the holes from being sealed by a blocking surface.
Ultimately, loss of electrolyte, due to evaporation (cell dryout), can cause a cell to stop functioning before complete discharge. The egress of water from inside the metal-air battery cells is caused by a higher partial pressure of water (ppH2O) on the interior of the battery cell than on the exterior of the battery cell. Under such conditions, moisture will diffuse through the air access holes. Since the ppH2O inside the battery cell is usually greater than the ppH2O of the atmosphere, moisture normally diffuses out of the battery cell.
To reduce dryout, the sizing of the air access holes on the gas-exchange wall of the metal-air battery cell is designed to strike the most favorable balance between the demand for oxygen and inhibition of evaporative loss of water from the battery cell. This balance is struck by making the hole size as small as practical, which is essentially a question of manufacturing cost-effect, and by spacing the holes as far apart as possible without substantially reducing the efficacy of the battery cell""s oxygen take-up.
To prevent the entry of water into the battery pack and the accidental shorting of the metal-air battery cells, air access holes on the battery pack case are sized and/or positioned to inhibit the entry of water into the battery pack. This prevents water from contacting the battery cells and causing shorts. The battery pack case may also be constructed of hydrophobic material. In this case, holes on the case may be sized small enough to cause water to bead up, preventing the penetration of water through the case. Also, air access holes in the battery pack case can be located on bumps or ridges on the case, creating channels (between the bumps or ridges) through which water is directed away from the air access holes.
In an additional embodiment, a hydrophobic material is placed inside the battery cell case to prevent the leakage of electrolyte. Electrolyte may leak out of the battery cell and into the battery case when the cell is exposed to adverse conditions, such as when the cell is subject to high temperatures or high pressure. The material reduces the gravity and likelihood of electrolyte leakage.
To provide for the secure placement of the metal-air battery cells in the battery pack (battery cell stability in a pack), a plurality of battery cells are held by an internal support structure that separates the battery cells and keeps them from moving around. One type of structure contains a plurality of compartments into which the battery cells may be positioned. The compartments have projections that secure the battery cells by a snap-fit. The structure may then be securely connected to the battery pack case. Alternatively, the battery pack case itself may be provided with a plurality of projections that allow the individual metal-air battery cells, or the structure containing the plurality of battery cells, to snap in place. Battery cell compartments can also be joined by a living hinge with each compartment containing standoffs to aid in the separation of the battery cells. To alleviate the problem due to the inevitable expansion of the metal-air battery cells (e.g., due to zinc-oxide formation), the support structure can be flexible so as to accommodate changes in the shape of the battery cells.
Another issue with metal-air batteries is the small space that consumers expect batteries to require in common high current portable electronic devices. The present invention uses prismatic metal-air battery cells designed to minimize wasted space by providing a high packing density, allowing for a compact battery pack.
Metal-air batteries cannot tolerate charging. However, many hands-free adapters automatically charge batteries when they are connected to the adapters. To prevent charging or limit charging to acceptable levels, internal circuitry or external components may be added to prevent the charging of battery cell (e.g., a current cutoff switch) or limit the charging of the battery cell to a controlled rate.
According to an embodiment, the invention provides a battery case housing at least one metal-air battery cell. The case has a holder supporting the battery cell(s) in a predefined position inside the case. The holder and a remainder of the case are configured to define, together with the battery cell(s), an air conduit inside the case. The air conduit can be any kind of internal space, the only requirement is that it define some kind of path along which air may flow between openings in a wall of the case. The flow path has a cross section with a hydraulic diameter that can easily be calculated. The conduit also has a flow length between openings at opposite ends thereof. The conduit is shaped to insure a minimum value of a ratio of the square of the hydraulic diameter to the length of the flow path is at least 0.5 mm. The openings may be sized to have minimum respective hydraulic diameters of at least 3 mm to allow for good air flow into and out of the air conduit. Preferably, the conduit hydraulic diameter is substantially uniform along the flow path.
According to another embodiment, the invention provides a battery case housing at least one metal-air battery cell. The cell(s) has a respective gas-exchange wall through which gas exchange between an interior and exterior of the cell(s) takes place. The case housing has a holder configured to support the cell(s) in (a) predefined position(s) inside the case. The holder and a remainder of the case are configured to define, together with the cell(s)"" gas-exchange wall, an internal volume inside the case. The case has at least one opening in its external walls to provide a gas exchange interface between the exterior of the case and the internal volume. The opening(s) has a combined area of at least 300 mm2/watt of peak power capacity of the cell(s) exchanging air gases through the opening(s). Preferably there are at least two openings on opposing sides of the internal volume with the internal volume connecting the two to form a flow conduit. The conduit has a cross section with a hydraulic diameter that can easily be calculated. The conduit also has a flow length between openings at opposite ends thereof. The conduit is shaped to insure a minimum value of a ratio of the square of the hydraulic diameter to the length of the flow path is at least 0.5 mm.
According to still another embodiment, the invention provides a battery case for housing at least one metal-air battery cell. The cell has a respective gas-exchange wall through which gas exchange between an interior and exterior of the cell(s) takes place. The case has a housing with at least one aperture providing communication between an exterior of the housing and the air conduit. Also, a holder is configured to support the cell(s) in a predefined position inside the case. The holder and the case are configured to define, together with the cell(s) at least one gas-exchange wall. An air conduit is defined by the case structure and at least part of the conduit is lined by the gas-exchange wall. The conduit has a clearance equal to a minimum dimension in a direction substantially normal to the cell(s)"" gas-exchange wall. The holder and the housing are further configured such that a distance between a portion of the cell(s)"" gas-exchange wall that is most remote from the aperture(s) is no greater than twenty times the overhead clearance. The overhead clearance is the thickness of the conduit in a direction normal to the gas-exchange wall. Preferably, in this embodiment, there are at least two apertures on opposing sides of the conduit and the conduit is characterized by a ratio of hydraulic diameter of flow cross section to flow length between the openings of at least 0.5 mm. Further, preferably in combination with the last feature or alone, the aperture(s) have a combined area of at least 300 mm2/watt of peak power capacity of the cell(s) exchanging air gases through the aperture(s).
According to still another embodiment, the invention provides a battery case for housing at least one metal-air battery cell. The cell(s) has at least one gas-exchange wall for permitting diffusion of gases between the interior cell(s) and the exterior of the cell(s). The case has a holder configured to support the cell(s) in a predefined position inside the case. The holder and a remainder of the case are configured to define, together with the cell(s), an air conduit inside the case. There are opening(s) in the case wall in communication with the air conduit. The conduit has a depth in a direction normal to a major plane of the gas-exchange wall(s) large enough to accommodate the expansion of the cell(s) while leaving a minimum of 2 mm remainder of the depth. Preferably, there are at least two openings on opposing ends of the conduit and the conduit is characterized by a ratio of hydraulic diameter of flow cross section to flow length between the openings of at least 0.5 mm. Preferably, alone or in concert with the prior features, the opening(s) has a combined area of at least 300 mm2/watt of peak power capacity of the cell(s) exchanging air gases through the opening(s). Preferably, either alone or in addition to the previous features, the opening(s) has a hydraulic diameter of at least 3 mm.
According to still another embodiment, the invention provides a battery case for supporting at least one metal-air battery cell. The cell has at least one surface with holes for permitting diffusion of gas therethrough. The case has a holder configured to support the cell(s) in a predefined position inside the case. The holder and a remainder of the case are configured to define, together with the cell(s), an air conduit inside the case. Openings in the case wall provide communication with the air conduit, at least two of the openings lying at opposite ends of the conduit. Preferably, the first and second openings can be joined by a straight line that passes through conduit without touching boundaries of the conduit. Preferably, the conduit has a first major axis defining a first linear flow path linking first and second apertures and the openings lie directly adjacent the conduit to minimize a flow resistance of the conduit. Preferably, the openings are sized to be a substantial fraction of a hydraulic diameter of the conduit. Preferably, the conduit is characterized by a ratio of hydraulic diameter of flow cross section to flow length between the of the openings of at least 0.5 mm. Further, it is preferable that the openings have respective hydraulic diameters of at least 3 mm.
According to still another embodiment, the invention provides a battery case for supporting at least one metal-air battery cell. The case has a holder configured to support the cell(s) in a predefined position inside the case. The holder and a remainder of the case are configured to define, together with the cell(s), an air conduit inside the case. At least one opening in the case wall is communication with the air conduit. The conduit has a substantially uniform hydraulic diameter. The cell(s) has a respective gas-exchange wall through which gas exchange between an interior and exterior of the cell(s) takes place. The conduit has a clearance equal to a minimum dimension in a direction substantially normal to the cell(s)"" gas-exchange wall. The holder and the housing are further configured such that a certain ratio of distances is no more than twenty. The numerator of this ratio is the distance between a portion of the cell(s)"" gas-exchange wall that is most remote from an opening to that nearest opening(s). The denominator is the overhead clearance. That is, one finds the portion of gas-exchange wall (or the hole through which gas is exchanged) that is furthest from a case opening. Then measure the distance from the nearest opening to that portion (or cell hole). This distance is the numerator of the ratio. The denominator is simply the distance in a direction normal to the cell gas-exchange wall to the opposite face of the conduit. Preferably the opening(s) is at least two openings on opposing ends of the conduit and the conduit is characterized by a ratio of hydraulic diameter of flow cross section to flow length between the of the openings of at least 0.5 mm. Also, preferably, the opening(s) has a combined area of at least 300 mm2/watt of peak power capacity of the cell(s) exchanging air gases through the opening(s).
According to still another embodiment, the invention provides a battery case for supporting at least one metal-air battery cell. The case has a holder configured to support the cell(s) in a predefined position inside the case. The holder and a remainder of the case are configured to define, together with the cell(s), an air conduit inside the case. Openings in the case wall provide communication with the conduit. The openings are located directly adjacent the conduit such that a substantially contiguous flow path is defined, whereby a possibility of flow short-circuiting of the conduit by any two of the openings is minimized. Preferably, at least two of the openings lie at opposite ends of the conduit. Also preferably, the conduit is substantially a sole means for air to flow from at least two first and second oppositely positioned openings in the case.
According to still another embodiment, the invention provides a battery pack with a housing. The housing has apertures permitting gas exchange between the interior and the exterior of the housing. Electrochemical cells exchange gas with ambient air via gas-exchange wall coinciding with a major plane thereof. The cells are supported inside the case. Each cell also has a back surface opposite the gas-exchange wall, the gas-exchange wall allows for gas exchange between the interior and exterior of the cells. First and second of the cells are arranged with the back surfaces adjacent and held in a position such that the gas-exchange wall of the first of the cells faces the housing. This defines a first air space between the housing and the gas-exchange wall. The gas-exchange wall of the second of the cells faces a second air space. A thickness of the second air space is substantially thicker than a thickness of the first air space. Preferably, the first interior space is at least 0.5 mm in thickness, the thickness being a dimension normal to the gas-exchange wall. Preferably, the second interior space is at least 4 mm in thickness, the thickness being a dimension normal to the gas-exchange wall. Preferably, the second interior space is at least 2.5 mm in thickness.
According to still another embodiment, the invention provides a battery pack with a housing having apertures permitting gas exchange between the interior and exterior thereof. Prismatic metal-air electrochemical cells are supported inside the housing. Each of the cells has at least one gas-exchange wall coinciding with a major plane thereof and a back surface opposite the gas-exchange wall. The gas-exchange wall is such that gas exchange between respective interiors and exteriors of the cells may occur. First and second of the cells are arranged with the gas-exchange walls thereof facing and opposite each other such that their gas-exchange walls define an air space therebetween. A thickness of the air space is a minimum of 0.5 mm, the thickness being a dimension normal to the gas-exchange walls of the first and second of the cells.
According to still another embodiment, the invention provides a battery pack with a housing. The housing has at least one aperture permitting a gas exchange between an interior and an exterior thereof. Prismatic metal-air electrochemical cells are supported inside the housing. Each of the cells has at least one gas-exchange wall coinciding with a major plane thereof and a back surface opposite the gas-exchange wall, the gas-exchange wall being such that gas exchange between respective interiors and exteriors of the cells may occur. First and second of the cells are arranged with the gas-exchange walls thereof facing and opposite each other such that their gas-exchange walls define an air space therebetween. A thickness of the air space is a minimum of 4 mm, the thickness being a dimension normal to the gas-exchange walls of the first and second of the cells. Preferably, a distance between a portion of the exchange surfaces most remote from an aperture(s) to the closest aperture is no greater than twenty times the thickness of the air space. Preferably, there are at least two apertures on opposing ends of the air space to define a flow conduit for bulk flow of air and the conduit is characterized by a ratio of a square of the hydraulic diameter of flow cross section to flow length between the apertures of at least 0.5 mm. Preferably, the aperture(s) has a combined area of at least 300 mm2/watt of peak power capacity of the cells exchanging air gases through the aperture(s). Preferably, the pack has the following features in combination: (1) aperture(s) with a combined area of at least 300 mm2/watt of peak power capacity of the cells exchanging air gases through the aperture(s), (2) there are at least two apertures on opposing ends of the air space to define a flow conduit for bulk flow of air, and (3) the conduit is characterized by a ratio of hydraulic diameter of flow cross section to flow length between the apertures of at least 0.5 mm. Preferably, at least some of the aperture(s) are immediately adjacent the air space, thereby defining a contiguous unobstructed path for exchange of air gases.
According to still another embodiment, the invention provides a battery case connectable to a portable hand-held device for supporting at least one metal-air battery cell. The case has a holder configured to support the cell(s) in a predefined position inside the case. The holder and a remainder of the case are configured to define, together with the cell(s), an air conduit inside the case. Openings in the case wall provide air communication with the conduit. A first and a second series of the openings are positioned such that, for all possible normal manual holding positions of the case hand-held device-combination, at least one of the first series and at least one of the second series remain unobstructed. The holes are sized, shaped, numbered and/or located to insure that flow through the conduit between at least one of the first series at least one of the second series remains possible. Preferably, the first and second series of openings lie at opposite ends of the conduit. Preferably, the case is shaped such that a substantial number of the openings cannot be blocked by a flat surface.
According to still another embodiment, the invention provides a battery case for supporting at least one metal-air battery cell. The case has an internal support for holding the cell(s) and a housing with openings to supply air to the cell(s). The case has channels defined in a surface of the case. The openings are located in the channels such that a surface resting against the case is prevented from covering the openings thereby permitting air to enter the openings when the flat surface rests against the case.
According to still another embodiment, the invention provides a battery case for supporting at least one metal-air battery cell, having a housing with openings therein. A material of the housing and a size of the openings in the housing are such that a surface tension of water substantially prevents entry of water droplets into the housing. The housing has a hydrophobic surface.
According to still another embodiment, the invention provides a battery case for supporting at least one metal-air battery cell. The case has a housing with openings therein. The housing has raised portions defining channels for conducting fluid therebetween. The openings are located on the raised portions such that the openings are maintained at positions remote from liquid in the channels. Thus, the liquid is conducted away from the openings.
According to still another embodiment, the invention provides a metal-air battery power supply. The power supply has a current limiter, and a metal-air battery cell. There is a connector of the metal-air battery cell that is connectable to a charging source. The device has a switch between the battery cell and the connector configured to selectively interpose the current limiter between the connector and the battery cell.
According to still another embodiment, the invention provides a metal-air battery power supply. The power supply has a current limiter and a metal-air battery cell. There is a connector of the metal-air battery cell that is connectable to a charging source. The device has a controller programmed to selectively interpose the current limiter between the connector and the battery cell.
According to still another embodiment, the invention provides a metal-air battery power supply with a metal-air battery cell. The power supply is for connection to a portable device. The portable device has terminals for connecting to a portable power source. An adapter on the portable device is connectable to a battery charger connected through the portable device to the terminals. The battery cell has a current limiter connectable between the terminals and the metal-air battery cell to prevent over-charging of the battery cell. Preferably, the power supply has a controller programmed to selectively interpose the current limiter between the terminals and the cell(s). Preferably, a voltage sensor is connected to detect a voltage across terminals of the connector. Also, a controller is connected to control the switch responsively to the voltage sensor such that a voltage indicating a charging voltage applied across the terminals causes the current limiter to be connected between the battery cell and the terminals.
According to still another embodiment, the invention provides a metal-air battery power supply with a metal-air battery cell. The power supply is for connection to a portable device. The portable device has terminals for connecting to a portable power source. An adapter on the portable device is connectable to a battery charger connected through the portable device to the terminals. The power supply has a movable cover on the battery positionable in a blocking position with respect to the adapter to prevent connection of the adapter to the charger. An electrical switch is connected to the movable cover such that when the movable cover is placed in the blocking position, the electrical switch directly connects the battery to the terminals and when the movable cover is in a position other than the blocking position, the electrical switch connects the battery to the terminals through a current limiter. This device is applicable to a cell phone.
According to still another embodiment, the invention provides a metal-air battery power supply with a metal-air battery cell. The power supply is for connection to a portable device. The portable device has terminals for connecting to a portable power source. An adapter on the portable device is connectable to a battery charger connected through the portable device to the terminals. There is a movable cover on the battery is positionable in a blocking position with respect to the adapter to prevent connection of the adapter to the charger. A connecting device is connected to the movable cover such that when the movable cover is placed in the blocking position, the connecting device directly connects the battery to the terminals and when the movable cover is in a position other than the blocking position, the connecting device connects the battery to the terminals through a current limiter.
According to still another embodiment, the invention provides a metal-air battery power supply with a metal-air battery cell. The power supply is for connection to a portable device. The portable device has terminals for connecting to a portable power source. An adapter on the portable device is connectable to a battery charger connected through the portable device to the terminals. A movable cover on the battery positionable in a blocking position with respect to the adapter to prevent connection of the adapter to the charger. An electrical switch is connected to the movable cover such that when the movable cover is placed in the blocking position, the electrical switch directly connects the battery to the terminals and when the movable cover is in a position other than the blocking position, the electrical switch disconnects the battery from the terminals.
According to still another embodiment, the invention provides a metal-air battery power supply with a metal-air battery cell. The power supply is for connection to a portable device. The portable device has terminals for connecting to a portable power source. An adapter on the portable device is connectable to a battery charger connected through the portable device to the terminals. A blocking device on the battery is positionable in a blocking position with respect to the adapter to prevent connection of the adapter to the charger. A connecting device is connected to the blocking device such that when the blocking device is placed in the blocking position, the connecting device directly connects the battery to the terminals and when the movable cover is in a position other than the blocking position, the connecting device disconnects the battery from the terminals.
According to still another embodiment, the invention provides a battery case. The case has a housing and at least two metal-air battery cells inside the housing. The battery cells are supported in adjacent juxtaposition with major planes thereof substantially coinciding. The housing has a plurality of apertures to allow exchange of gases between an inside of the housing and an outside of the housing. The housing has a surface substantially parallel with the major planes and spaced from the major planes by 0.02 mm to 2.0 mm, thereby defining a plenum between the housing and the metal-air battery cells.
According to still another embodiment, the invention provides a battery case. The case has a housing with at least two metal-air battery cells inside the housing. The cells are supported in adjacent juxtaposition. The housing has a plurality of apertures to allow exchange of gases between an inside of the housing and an outside of the housing. The housing has a surface substantially parallel with the major plane of the battery cells and spaced from at least one of the battery cells the major planes by 0.02 mm to 2.0 mm, thereby defining a first plenum between the housing and the metal-air battery cells. The cells are spaced apart by a distance of at least 3 mm such that a second plenum is defined between the battery cells. Preferably, the cells are at least four metal-air battery cells and third and fourth of the four metal-air battery cells are arranged with their respective major surfaces substantially parallel with first and second of the at least four battery cells and spaced apart by 0.5 mm to 10 mm to define a second plenum therebetween. Preferably, also, the second plenum has a substantially constant hydraulic diameter. Preferably, the housing has at least two holes opposite each other across a gap spanned by the metal-air battery cells thereby defining a flow conduit for bulk flow of air. The conduit is characterized by a ratio of hydraulic diameter of flow cross section to flow length between the apertures of at least 0.5 mm.
According to still another embodiment, the invention provides a battery case for metal-air battery cells that expand during a discharge cycle thereof. The case has a housing containing a support structure for supporting metal-air battery cells. The support structure contains a plurality-of projections into which the battery cells are inserted such that the projections secure the battery cells to the support structure. The projections contain recesses for receiving the battery cells. The projections are shaped such that the recesses allow for the battery cells to expand without resulting in a substantial distortion of the support structure. Preferably, the cells are aligned in layers such that the longitudinal axes along the layers defines a plenum between the battery cells.
According to still another embodiment, the invention provides a battery case for metal-air battery cells that expand during a discharge cycle thereof. The case has a housing containing a support structure for supporting metal-air battery cells. The support structure contains a plurality of projections into which the battery cells are inserted such that the projections secure the battery cells to the support structure. The support structure is configured and of such material that the support structure may flex sufficiently to accommodate the expansion without permitting the battery cells to become unsupported thereby.
According to still another embodiment, the invention provides a battery case for metal-air battery cells, the case. The case has a housing containing a support structure for supporting a plurality of metal-air battery cells. The support structure has first and a second support portions, each portion has recesses for receiving a respective one of the battery cells. Each portion is linked by an integral hinge. The first portion and the second portion have integral standoffs positioned to hold the battery cells held in the first portion a specified distance from the battery cells held in the second portion when the first and second portions are arranged in a parallel relationship inside the housing. Preferably, the case includes diffusing elements positioned above the respective battery cells. The recesses define trays into which the respective battery cells fit. The diffusing element is formed of a material such that a gas exchange through the diffusing elements and between the respective battery cells and an outside of the case is permitted. Preferably, the recesses define trays into which the respective battery cells fit, the trays is closed with an absorbent material attached thereto. In this way, the trays are able to hold any spilled substance emerging from the respective battery cells. Also a gas permeable membrane may be attached to the tray, enclosing the respective battery cells to block an intrusion of liquid into, or leakage of liquid from, the battery cells. The integral hinge may provide at least 180 degree angular movement between the longitudinal axes of the first support portion and the second support portion.
According to still another embodiment, the invention provides a battery case for housing at least one metal-air battery cell with air holes on a surface thereof. The case has a case element shaped to have at least one opening on a surface, thereof. The case also has a holder enclosed by the case element and configured to support the metal-air battery cell. A diffusing element is positioned between the battery cell surface with air holes and the case element such that the battery cell surface with air holes is separated from the case element. The diffusing element is formed of a material such that a gas exchange through the diffusing element and between an outside of the case element and the battery cell is permitted. Optionally, the diffusing element contacts the battery cell surface with air holes. The diffusing element may have a thickness greater that 4 mm, the thickness measured between a surface that contacts the battery cell surface with air holes and a surface that contacts the case element surface with the opening(s). The diffusing element may be formed of an absorbent material. The holder may be formed integrally with the case.
According to still another embodiment, the invention provides a battery case for housing at least two metal-air battery cells with air holes on a respective surface, thereof. The case has a case element shaped to have at least one opening. A holder is enclosed by the case element and is configured to support the battery cells. A diffusing element is positioned between the battery cells such that the battery cells are separated from each other. The diffusing element is formed of a material such that a gas exchange through the diffusing element and between an outside of the case element and at least one of the battery cells is permitted. The diffusing element may contact the surface of the at least one of the battery cells. The diffusing element may contact respective surfaces of the battery cells. The holder may be integral to the case element.
According to still another embodiment, the invention provides a battery case for supporting at least one metal-air battery cell to power an electronic device has a defined peak current load. The case has holes and a holder configured to support the cell(s) in a predefined position inside the case. The case is substantially concave along a surface of the case in relation to the battery cell such that a sufficient number of holes remain unobstructed when the case is placed against a flat surface to satisfy the peak current load. The case may be substantially concave in relation to the battery cell along the case""s longitudinal axis. The case may be substantially concave in relation to the battery cell along the width of the case.
According to still another embodiment, the invention provides a battery case for supporting at least one metal-air battery cell. The case has a housing containing a support structure for supporting metal-air battery cells. The support structure has a first surface onto which the battery cells are attached. The support structure has a second surface which attaches to the case. The support structure is made of such material that the support structure allows for the battery cells to expand. The support structure may contain punched out holes with substantially the same width and length as the battery cells such that the battery cells are press-fittable into the holes.
According to still another embodiment, the invention provides a battery case for supporting at least one metal-air battery cell to power an electronic device that has a defined peak current load. The case has a holder configured to support the cell(s) in a predefined position inside the case. The case contains a plurality of projections substantially perpendicular to the exterior surface of the case. The projections are positioned on the case such that a sufficient number of holes remain unobstructed when the case is placed against a flat surface to satisfy the peak current load.
According to still another embodiment, the invention provides a battery case for supporting at least one metal-air battery cell. The case has a housing with holes and an internal support structure for holding the cell(s) fittable inside the housing. A liquid impermeable covering is positioned over the housing such that an intrusion of liquid into a space occupied by the cell(s) is prevented.
According to still another embodiment, the invention provides a battery case for supporting at least one metal-air battery cell. The case has a housing with holes and an internal support structure for holding the cell(s) fittable inside the housing. A liquid impermeable covering attached to an interior surface of the housing such that an intrusion of liquid into a space occupied by the cell(s) is prevented.
According to still another embodiment, the invention provides a battery case for supporting at least one metal-air battery cell. The case has a housing with holes and an internal support structure for holding the cell(s) fittable inside the housing. A liquid impermeable covering is positioned over the internal support structure such that an intrusion of liquid into a space occupied by the cell(s) is prevented. At least two layers of the battery cells may be supported within the battery case and a liquid impermeable covering over each of the layers of battery cells such that an intrusion of liquid into a space occupied by the cell(s) is prevented.
According to still another embodiment, the invention provides a battery case for housing at least one metal-air battery cell. A holder is configured to support the cell(s) in a predefined position within the battery case. The battery cells and battery case are configured to define at least one air conduit inside the case. At least one opening in the battery case is in communication with the air conduit. The openings in the battery case permit the transport of oxygen into the battery case at a rate of 0.04-0.5 cc O2 per second. The openings may permit the transport of approximately 0.2 cc O2 per second into the battery case.
According to still another embodiment, the invention provides a battery pack containing at least one metal-air battery cell. The case has a first substantially rectangular case component with a first major surface and contiguous side walls for encompassing a cathode of the cell(s). It also has a second substantially rectangular case component attached to the first tray-like case component with a second major surface and contiguous side walls for encompassing an anode of the cell(s). The first major surface has a plurality of air access openings. The air access openings have a diameter of approximately 0.5 mm.
According to still another embodiment, the invention provides a battery pack contains at least one metal-air battery cell. The pack has a first substantially rectangular case component with a first major surface and contiguous side walls for encompassing a cathode side of the cell(s) and a second substantially rectangular case component attached to the first tray-like case component. The latter has a second major surface and contiguous side walls for encompassing an anode side of the cell(s). The first major surface has a plurality of air access openings. The number of the air access openings insures that the total current produced by the pack is at least 80 percent of a maximum possible current capacity under all conditions. This includes when some holes are blocked by a user""s hand, the appliance is placed on a surface, or other normal operating conditions.
According to still another embodiment, the invention provides a battery case for housing at least one metal-air battery cell with a plurality of air access openings. The case has at least one surface with a plurality of openings for permitting diffusion of gases therethrough. The metal-air battery cells have a plurality of air access openings on the gas-exchange wall of the metal-air battery cells. The plurality of openings on the battery case have a combined area of at least twice the combined area of the air access openings on the metal-air battery cells within the battery case.
According to still another embodiment, the invention provides a battery pack. The pack has a housing with apertures permitting gas exchange between an interior and an exterior thereof. Prismatic metal-air electrochemical cells are supported inside the housing and each of the cells has at least one gas-exchange wall coinciding with a major plane of the cell. Each cell also has a back surface opposite the gas-exchange wall. The gas-exchange wall is provided to allow gas exchange between respective interiors and exteriors of the cells. First and second of the cells are arranged with the gas-exchange walls thereof facing in a same direction toward a major surface of the housing such that a first air space is defined. The first air space is bounded by the gas-exchange wall of the first of the cells and the second of the cells. The arrangement is also such that a second air space, bounded by the gas-exchange wall of the second of the cells and the housing is defined. A thickness of the first air space is a minimum of 3 mm, the thickness being a dimension normal to the gas-exchange walls of the first and second of the cells.
According to still another embodiment, the invention provides a battery pack with a housing. The housing has apertures permitting gas exchange between an interior and an exterior of the housing. Prismatic metal-air electrochemical cells are supported inside the housing, each of the cells has at least one gas-exchange wall coinciding with a major plane thereof. There is also a back surface opposite the gas-exchange wall. The gas-exchange wall is such that gas exchange between respective interiors and exteriors of the cells may occur. First and second of the cells are arranged with the gas-exchange walls thereof facing in a same direction toward a major surface of the housing. This arrangement defines a first air space, bounded by the gas-exchange wall of the first of the cells and the second of the cells. The arrangement is such that a second air space, bounded by the gas-exchange wall of the second of the cells and the housing, is also defined. A thickness of the second air space is a minimum of 0.5 mm, the thickness being a dimension normal to the gas-exchange walls of the first and second of the cells.
According to still another embodiment, the invention provides a battery pack with a housing. The housing is constructed to permit an exchange of gases between the interior and the exterior. At least one electrochemical cell is held inside the housing. The one electrochemical cell has a respective gas-exchange wall through which gas is exchanged between an interior and exterior of the cell(s), the gas-exchange wall coinciding with a major plane of the at least one electrochemical cell. The electrochemical cell is located inside the housing such as to define an air space with a clearance equal to a minimum dimension in a direction substantially normal to the electrochemical cell gas-exchange wall. The holder and the housing are further configured such that a distance between a portion of the cell(s) gas-exchange wall that is most remote from a closest portion of the housing through which gas exchange between the interior and exterior of the housing, the closest portion being no greater than twenty times the overhead clearance. That is, the distance of this portion to the closest part of the housing where gas exchange occurs is no more than 20 times the overhead clearance.
According to still another embodiment, the invention provides a battery pack, with a housing. The housing has openings in a wall thereof to permit an exchange of gases between an inside of the housing and an outside of the housing. The pack has at least one electrochemical cell with holes in at least one major surface of a case thereof. The major surface(s) faces the wall. A spacing of the openings and a spacing of the holes together with a position of the at least one electrochemical cell are such that the holes and the openings are substantially aligned. Preferably, the openings are shaped such that their cross-sectional area decreases, either step-wise or progressively, in a respective axial direction from an interior surface of the housing toward an exterior surface of the housing.
According to still another embodiment, the invention provides a package for encasing an electrochemical device requiring an ambient gas. The package has an enclosure capable of encasing the electrochemical device. The enclosure is at least partly formed of a material that permits diffusion of the ambient gas into and out of the enclosure. Preferably, the enclosure has a moisture permeability of less than 3 mg H2O/day/300 cm2. The enclosure has an enclosing element and at least one sheet, the enclosing element having at least one opening. The sheet(s) cover the opening(s) and is attached to the enclosing element. The sheet may be formed from a material that permits diffusion of the ambient gas. The size of the opening(s) and a material of the at least one sheet may be such that the enclosure has a moisture permeability of less than 3 mg H2O/day/300 cm2. The enclosing element has a moisture permeability of less than 0.5 mg H2O/day/300 cm2.
The invention will be described in connection with certain preferred embodiments, with reference to the following illustrative figures so that it may be more fully understood.
With reference to the figures, it is stressed that the particulars shown are by way of example and for purposes of illustrative discussion of the preferred embodiments of the present invention only, and are presented in the cause of providing what is believed to be the most useful and readily understood description of the principles and conceptual aspects of the invention. In this regard, no attempt is made to show structural details of the invention in more detail than is necessary for a fundamental understanding of the invention, the description taken with the drawings making apparent to those skilled in the art how the several forms of the invention may be embodied in practice.